Funeral Held For NYPD Detective Killed During Attempted Robbery In Queens

In the email sent to the entire department obtained by ABC News, officials stressed there were "no specific threats" being made against the department, but that desk officers was ensure that every station house security post is staffed at all times.

Federal authorities reportedly notified the NYPD about the threat after they took an alleged MS-13 gang member into custody who they believed had made threats against police officers in the Bronx and other parts of the city.

The warning to officers comes after suspect Robert Williams, 45, allegedly walked up to a police van last week, asking the officers for directions before pulling out a gun and shooting Officer Paul Stroffolino, in the neck. His partner took the wounded officer to a local hospital.

Williams then allegedly walked into the 41st Precinct the next morning, and opened fire at officers and a civilian employee. One police lieutenant, Lt. Jose Gautreaux was shot in the arm, officials said.

The suspect was quickly arrested after he ran out of bullets and charged with 14 attempted murder counts. He's due back in court Friday morning.

“There is still much that we don't know about what happened and what led up to this incident,” attorney Tom Klein said in a statement to NBC New York. “We look forward to investigating and learning more so that we can best represent Mr. Williams."

Williams allegedly told police in a rambling statement that he was angry at police because of an encounter he had two years ago during a DUI arrest in 2018.